As the bug 6969236 demonstrated by breaking Eclipse, the rebranding changes made to the JDK (Sun->Oracle) is not without risk.
This RFE is an attempt at providing an easy way to determine what kind of jdk installation is available, without resorting to parsing OS dependent fields from inside binary files.
This RFE is being discussed at: https://bugs.eclipse.org/bugs/show_bug.cgi?id=321390
It may not be able to provide an answer for all JDK installations, but could be a step in the right direction.

Comments

EVALUATION
I could not find the file jdk.release. Kelly said the file ended up being called just "release" and should be at the top of an install tree. I checked the nightly build area under ws/build for all platforms and found
./linux-amd64-fastdebug/j2sdk-image/release
./linux-amd64-fastdebug/j2re-image/release
./linux-amd64/jre1.7.0/release
./linux-amd64/j2sdk-image/release
./linux-amd64/j2re-image/release
./solaris-amd64/j2sdk-image/release
./solaris-amd64/j2re-image/release
./solaris-amd64/jre1.7.0/release
./solaris-amd64-fastdebug/j2sdk-image/release
./solaris-amd64-fastdebug/j2re-image/release
./linux-i586/j2sdk-image/release
./linux-i586/jre1.7.0/release
./linux-i586/j2re-image/release
./linux-i586-fastdebug/j2sdk-image/release
./linux-i586-fastdebug/j2re-image/release
./solaris-i586/j2sdk-image/release
./solaris-i586/j2re-image/release
./solaris-i586/jre1.7.0/release
./solaris-i586-fastdebug/j2sdk-image/release
./solaris-i586-fastdebug/j2re-image/release
./windows-i586/j2re-image/release
./windows-i586/j2sdk-image/release
./windows-amd64/j2re-image/release
./windows-amd64/j2sdk-image/release
./windows-amd64-fastdebug/j2re-image/release
./windows-amd64-fastdebug/j2sdk-image/release
./windows-i586-fastdebug/j2re-image/release
./windows-i586-fastdebug/j2sdk-image/release
./solaris-sparcv9/j2sdk-image/release
./solaris-sparcv9/jre1.7.0/release
./solaris-sparcv9/j2re-image/release
./solaris-sparc/j2re-image/release
./solaris-sparc/j2sdk-image/release
./solaris-sparc/jre1.7.0/release
./solaris-sparcv9-fastdebug/j2sdk-image/release
./solaris-sparcv9-fastdebug/j2re-image/release
./solaris-sparc-fastdebug/j2sdk-image/release
./solaris-sparc-fastdebug/j2re-image/release
Here are a few examples of the content:
more windows-i586/j2sdk-image/release
JAVA_VERSION=\1.7.0\nOS_NAME=\Windows\nOS_VERSION=\5.1\nOS_ARCH=\i586\n
more windows-amd64-fastdebug/j2re-image/release
JAVA_VERSION=\1.7.0\nOS_NAME=\Windows\nOS_VERSION=\5.2\nOS_ARCH=\amd64\n
more solaris-sparcv9/jre1.7.0/release
JAVA_VERSION="1.7.0"
OS_NAME="SunOS"
OS_VERSION="5.10"
OS_ARCH="sparcv9"
more linux-amd64/j2re-image/release
JAVA_VERSION="1.7.0"
OS_NAME="Linux"
OS_VERSION="2.6"
OS_ARCH="amd64"